The immediate goal of the research proposed is to determine the quantitative relationship between body movement and blood pressure in the routine everyday environment. The long-term goal is to improve the accuracy and clinical interpretation of 24 hour blood pressure measures by explicitly taking into account the influence of body movement on blood pressure and its measurement. There is enormous variability in blood pressure in the course of a routine day. Pronounced blood pressure variability presents major difficulties in evaluating and treating an estimated 20 million Americans with borderline hypertension. Much of the blood pressure variability is behaviorally induced. Two factors in behavior are known to influence blood pressure, body movement (physical activity) and emotion. One hundred normotensive adults and 50 high risk and low risk children will wear portable noninvasive devices to record blood pressure and physical activity as they go about their normal daily activities for a 24 hour period. Blood pressure will be read automatically every 15 min during the day and every 30 min during sleep. Following each daytime reading the subject will record his behavioral activity (e.g., climbing stairs, talking on the telephone) and emotion or mood (e.g., anger, tension) on computer scorable diary cards. Body movement will be monitored continuously using small microcomputer based accelerometers attached to the body. Blood pressure, body movement, and mood data will be analyzed by correlation and linear regression methods to determine to what extent moment to moment changes in blood pressure are related to changes in physical activity and emotional intensity in the regular everyday environment at home and at work.